[0001] The present invention relates generally to methods of making monomer materials, and,
more particularly, to methods of making addition polymerizable, aromatic amine or
oligoaromatic phenol arylcyclobutene-containing monomers or resins having one or more
aryloxy, such as phenoxy, or oligophenolic groups comprising reacting an alpha-halide
(a-halide) or strong acid conjugate leaving group, such as a sulfonate leaving group,
for example, an o-tosyl or triflate leaving group, containing arylcyclobutene compound,
such as a 1-bromobenzocyclobutene (a-Br BCB), with an hydroxyl functional aromatic
monomer or oligoaromatic resin containing an addition polymerizable group, containing
an amine group, or an oligoaromatic resin containing one or more phenol ring or phenolic
hydroxyl group. The hydroxyl functional aromatic monomer or oligoaromatic resin is
formed by deprotecting it in organic alkali and a polar solvent to remove an organic
alkali cleavable protecting group from a protecting group containing aromatic monomer
or oligoaromatic resin.
[0002] Vinyl benzocyclobutene (vinyl BCB) styrenic copolymers provide many of the dielectric
benefits known BCB containing dielectrics at a significantly reduced cost. However,
unsubstituted BCB monomers require a 250 °C temperature for 1 hour for cure, which
renders them unsuitable for use with many polymer or plastic materials. Substitution
of the BCB ring can afford reduced cure temperatures, but often requires several additional
synthetic steps and often results in low monomer yields (<70%) in unstable monomer
compounds. For example, known alkoxy substituted BCBs do not survive thermal radical
polymerizations due to ring opening polymerization of the BCB and so are unsuitable
for applications which require orthogonal cure among addition and ring opening.
[0003] Previously,
Harth et al. in "Synthesis of low-temperature cross-linker and utilization," Polymer
Chemistry, 2012, 3(4), at 857-860, teach a 1-subtituted alkoxy BCB having the alkoxy group on the cyclobutene ring,
which is grafted to a poly(acrylic acid) post-polymerization to impart a low temperature
cure property for the BCB groups. Recent experiments produced a 1-alkoxy methacrylate
BCB and isolated the monomer through use of an expensive silver catalyst; however,
the material was unstable at 80°C where conventional free radical polymerizations
are carried out leading to a styrenic polymer that is highly crosslinked and not further
curable through a Diels Alder cycloaddition.
[0004] Further, aliphatic alkoxy BCBs are thermally processed at too low a temperature for
many applications, such as spin coating on a wafer and subsequent removal of the solvent
owing to the high boiling point of solvents required for safe operation in semiconductor
fabrication. Such aliphatic alkoxy linkages are known to lower ring opening thereby
disabling the orthogonal Diels Alder reaction.
[0005] The present inventors have sought to solve the problem of providing a simple method
for making a stable addition polymerizable BCB monomer useful for making a dielectric
material that enables the provision of addition polymerized and ring opening cured
(co)polybenzocyclobutenes having a low dielectric constant and low dielectric loss.
STATEMENT OF THE INVENTION
[0006] In accordance with a first aspect of the present invention, a method of making a
monomer or resin composition comprises deprotecting or deacylating an addition polymerizable
or amine containing aromatic monomer or an oligoaromatic resin containing an organic
alkali cleavable protecting group, such as a C
2 to C
9 alkanoyl group, preferably, an acyl group; or an alkyl carbonate group, such as methyl
carbonate, preferably, the monomer or resin being an addition polymerizable group
containing monomer, or, more preferably, an acetoxystyrene, by hydrolyzing to remove
the organic alkali cleavable protecting group in organic alkali and a polar solvent
containing an excess of alkali C
1 to C
7 alkoxide, preferably, alkali C
1 to C
4 alkoxide or, more preferably, sodium methoxide to form an hydroxyl functional addition
polymerizable aromatic monomer, such as 4-vinyl phenol or 4-vinyl napthol; a hydroxyl
functional aromatic amine containing monomer, for example, 4-aminophenol; or an oligoaromatic
phenol compound containing one or more phenolic hydroxyl, such as a phenolic novolac
or resole; preferably, a hydroxystyrene, followed by; reacting via nucleophilic substitution
the resulting hydroxyl functional addition polymerizable aromatic monomer, hydroxyl
functional aromatic amine functional group containing monomer or hydroxyl functional
oligoaromatic compound with an alpha-halide (a-halide) or strong acid conjugate leaving
group containing arylcyclobutene compound, preferably, having a bromide, on the cyclobutene
ring, or, more preferably, a 1-bromobenzocyclobutene (a-Br BCB), in a polar solvent,
such as a polar protic solvent, such as an alkanol or alkanone, or polar aprotic solvent,
such as an ether, an alkyl ester or amide, preferably, a non-aqueous solvent or anhydrous
solvent, to yield a product arylcyclobutene-containing addition polymerizable monomer,
aromatic amine functional group monomer or oligoaromatic phenol having an ether linkage
from the cyclobutene ring to an aromatic group of the addition polymerizable aromatic
monomer, aromatic amine or oligoaromatic phenol, preferably, an oligoaromatic phenol
resin containing from one to six, more preferably, from two to four, arylcyclobutene
groups.
[0007] In accordance with the methods of making a monomer or resin composition of the first
aspect of the present invention, the reacting via nucleophilic substitution comprises
heating the hydroxyl functional addition polymerizable aromatic monomer, hydroxyl
functional aromatic amine containing monomer or hydroxyl functional oligaromatic compound
with the alpha-halide (a-halide) or strong acid conjugate leaving group containing
arylcyclobutene compound in an organic alkali and polar solvent to from 55 to 80 °C,
or, preferably, from 60 to 75 °C, preferably, in the presence of a free radical inhibitor.
[0008] In accordance with methods of making a monomer or resin composition of the first
aspect of the present invention, the hydroxyl functional addition polymerizable aromatic
monomer, hydroxyl functional aromatic amine containing monomer or hydroxyl functional
oligoaromatic compound formed by deprotecting or deacylating comprises a hydroxyl
functional addition polymerizable aromatic monomer chosen from a styrene alcohol;
a vinylphenol; an allyl phenol; an alkynyl phenol; a vinyl naphthol; a vinyl oligophenol;
a vinylphenol having multiple vinyl groups, preferably, 2 to 6 vinyl groups; a vinylphenol
having multiple vinyl groups and multiple aromatic rings, such as from 2 to 20 aromatic
rings, or, preferably, from 2 to 6 of each of vinyl groups and aromatic rings; an
allyloligophenol having from 2 to 20, or, preferably, from 2 to 6 aromatic rings or
phenolic rings; an alkynyloligophenol having from 2 to 20, or, preferably, from 2
to 6 aromatic rings or phenolic rings.
[0009] In accordance with the methods of making a monomer or resin composition of the first
aspect of the present invention, wherein when the hydroxyl functional addition polymerizable
aromatic monomer, hydroxyl functional aromatic amine or hydroxyl functional oligoaromatic
phenol formed by deprotecting or deacylating comprises a vinyl oligophenol having
from 2 to 10 aromatic rings or phenolic rings, an aminophenol, an amino oligophenol
or any oligoaromatic phenol, it is substantially free of aldehydes.
[0010] Preferably, the hydroxyl functional addition polymerizable aromatic monomer, hydroxyl
functional aromatic amine containing monomer or hydroxyl functional oligoaromatic
compound formed by deprotecting or deacylating comprises a compound of any of the
formulae (1) to (9) or (D), below:
wherein R is independently any of H, CH
3, CH
3CH
2-, -C(CH
3)
2-, - C(CH
3)(CH
2CH
3)-,-C(Ph
2))-, SO
2 or Ph-, wherein Ph is phenyl; and wherein n is an integer of from 0 to 10; and, further
wherein, when the hydroxyl functional monomer or resin is a hydroxyl functional aromatic
amine containing monomer, at least one aromatic ring contains an amine group.
[0011] In accordance with methods of making a monomer or resin composition of the first
aspect of the present invention, wherein the organic alkali cleavable protecting group
on the protecting group containing aromatic monomer or oligoaromatic resin is chosen
from a C
2 to C
9 alkanoyl group, such as acyl, alkyl substituted acyl, propionyl, butyryl, pivaloyl,
alkylpivaloyl, a halogenated acyl group, such as a trifluoro acyl group (other), a
benzoate or an alkyl benzoate; or an alkyl carbonate, such as a methyl carbonate or
a 9-fluoreneylmethyl carbonate (FMoc); preferably, a C
2 to C
7 alkanoyl group, or, more preferably, an acyl or alkyl substituted acyl group.
[0012] In accordance with methods of making a monomer or resin composition of the first
aspect of the present invention, the protecting group containing aromatic monomer
or oligoaromatic resin having an organic alkali cleavable protecting group can be
a compound of any of the formulae A1 or A2, below, wherein Ac represents an acyl or
alkyl substituted acyl, and R represents any of a C
1 to C
6 divalent aliphatic hydrocarbon radical, e.g. alkylene, such as methylene, secondary
and tertiary alkylenes, for example, isobutylene or tert-butylene or halogenated branched
alkylenes, such as ditrifluoromethyl-substituted alkylenes; or an ether containing
divalent hydrocarbon:
[0013] In accordance with methods of making a monomer or resin composition of the first
aspect of the present invention, the methods further comprise purifying the product
arylcyclobutene-containing addition polymerizable monomer, aromatic amine containing
momomer or oligoaromatic phenol resin having an ether linkage from the cyclobutene
ring to an aromatic group of the addition polymerizable aromatic monomer, aromatic
amine or oligoaromatic phenol, such as by extracting the monomer in an aqueous polar
solvent mixture, such as water and ethyl acetate,preferably, followed by removing
the aqueous component by extracting it with a base, an alkali metal halide salt, or
both, combining the organic residues from the monomer extract and the aqueous extraction,
and then drying the combined organic residues.
[0014] In accordance with methods of making a monomer or resin composition of the first
aspect of the present invention, the methods further comprise reacting the product
arylcyclobutene-containing aromatic amine having an ether linkage from the cyclobutene
ring to an aromatic group of the aromatic amine with an unsaturated anyhydride, preferably,
maleic anhydride, in the presence of a radical inhibitor to form an aromatic maleimide
of an arylcyclobutene-containing aromatic maleimide monomer having an ether linkage
from the cyclobutene ring to an aromatic group of the maleimide. Alternatively, other
unsaturated anhydrides can be used to generate polymerizable imides such as, itaconic
anhydride, 4-ethynyl phthallic anhydride, 4-methylethynyl phthallic anhydride, and
4-phenyl ethynyl phthallic anhydride.
[0015] In accordance with a second aspect of the present invention, monomer or resin compositions
comprise one or more arylcyclobutene-containing, such as a benzocyclobutene (BCB)-containing,
addition polymerizable monomer, aromatic amine or oligoaromatic phenol monomer or
resin having an ether linkage from the cyclobutene ring to an aromatic group of the
addition polymerizable aromatic monomer, aromatic amine or oligoaromatic phenol in
a purity of at least 90 wt,%, or, preferably, at least 95 wt.% of the composition,
preferably, as a solid.
[0016] In accordance with the monomer or resin compositions of the second aspect of the
present invention, wherein the monomer is substantially free of 2-methylbenzaldehyde,
as in the following formula V:
[0017] In accordance with the monomer or resin compositions of the second aspect of the
present invention, wherein the compositions comprise from less than 10 ppm, preferably,
less than 1 ppm, of an alkali or alkaline earth metal impurity.
[0018] In accordance with the monomer or resin compositions of the second aspect of the
present invention, the arylcyclobutene-containing monomer or resin contains an addition
polymerizable group, an amine group or two or more aromatic rings and is chosen from
a vinyl phenoxy BCB, vinylnaphthyl BCB, an allyl phenoxy BCB, an alkynyl phenoxy BCB,
a vinyl oligophenoxy BCB, an allyl oligophenoxy BCB, an aminophenoxy BCB, an amino
oligophenoxy BCB, a novolac phenoxy BCB or an oligophenolic BCB.
[0019] In accordance with the monomer or resin composition of the second aspect of the present
invention, the product preferably comprises an addition polymerizable group containing
arylcyclobutene monomer having two vinyl groups, wherein Ar is any of the following
formulae (1) to (9), below, and, wherein in the formulae (1) to (9), below, R = H,
CH
3, CH
3CH
2-, -C(CH
3)
2-, -C(CH
3)(CH
2CH
3)-, -C(Ph
2))-, SO
2 or Ph-, wherein Ph is phenyl:
[0020] In accordance with the monomer or resin composition of the second aspect of the present
invention, the product preferably comprises an arylcyclobutene containing oligoaromatic
phenol resin having multiple arylcyclobutene groups of any of the following formulae
(11), below:
wherein, Z = -CH
2-, -CH
2-CH
2-, -CH
2-Ar-CH
2-, a C
3 to C
4 alkylene or an ether, n is an integer from 0 to 8, preferably 0 to 4, and each of
R
1, R
2, R
3, R
4, R
5, R
6, R
7, R
8, R
9, R
10, and R
11, is independently H, deuterium, methyl or ethyl, preferably, H.
[0021] In accordance with the monomer or resin compositions of the second aspect of the
present invention, the monomer or resin compositions comprise the arylcyclobutene-containing
addition polymerizable monomer or the arylcyclobutene-containing aromatic maleimide
monomer and, further, comprise an aromatic addition polymerizable monomer, such as
styrene.
[0022] Unless otherwise indicated, conditions of temperature and pressure are ambient or
room temperature (RT) and standard pressure. All ranges recited are inclusive and
combinable.
[0023] Unless otherwise indicated, any term containing parentheses refers, alternatively,
to the whole term as if no parentheses were present and the term without them, and
combinations of each alternative. Thus, the term "(meth)acrylate" refers to an acrylate,
a methacrylate, or mixtures thereof.
[0024] As used herein, all amounts are percent by weight and all ratios are molar ratios,
unless otherwise noted.
[0025] All numerical ranges are inclusive of the endpoints and combinable in any order,
except where it is clear that such numerical ranges are constrained to add up to 100%.
[0026] As used herein, the articles "a", "an" and "the" refer to the singular and the plural.
As used herein, the term "alkyl" includes linear, branched and cyclic alkyl. Likewise,
"alkenyl" refers to linear, branched and cyclic alkenyl. "Aryl" refers to aromatic
carbocycles and aromatic heterocycles.
[0027] As used herein, the term "aliphatic" refers to an open-chain carbon-containing moiety,
such as alkyl, alkenyl and alkynyl moieties, which may be linear or branched. Also
as used herein, the term "alicyclic" refers to a cyclic aliphatic moiety, such as
cycloalkyl and cycloalkenyl. Such alicyclic moieties are non-aromatic, but may include
one or more carbon-carbon double bonds. "Halide" refers to fluoro, chloro, bromo,
and iodo. The term "(meth)acrylate" refers to both methacrylate and acrylate, and
likewise the term (meth)acrylamide refers to both methacrylamide and acrylamide.
[0028] Unless the context clearly indicates otherwise, by "substituted" alkyl, alkenyl,
or alkynyl is meant that one or more hydrogens on the alkyl, alkenyl, or alkynyl is
replaced with one or more substituents chosen from halide, hydroxy, C
1-10 alkoxy, amino, mono- or di-C
1-10 hydrocarbyl substituted amino, C
5-20 aryl, and substituted C
5-20 aryl.
[0029] Unless the context clearly indicates otherwise, by "substituted" aryl is meant that
one or more hydrogens on the aryl is replaced by one or more substituents chosen from
halide, hydroxy, C
1-10 alkyl, C
2-10 alkenyl, C
2-10 alkynyl, C
1-10 alkoxy, amino, mono- or di-C
1-10 hydrocarbyl substituted amino, C
5-20 aryl, and substituted C
5-20 aryl. "Alkyl" refers to an alkane radical, and includes alkane diradicals (alkylene)
and higher-radicals. Likewise, the terms "alkenyl", "alkynyl" and "aryl" refer to
the corresponding mono-, di- or higher-radicals of an alkene, alkyne and arene, respectively.
[0030] As used herein, the term "addition polymerizable group" means any unsaturation functional
group that polymerizes via addition polymerization, including vinyl, vinylidene or
allyl groups and any such group having any alkyl, alkoxy, S, N, P, O or Si heteroatom
containing hydrocarbon substituent or component, or any siloxy, cyano, aryl, alkylaryl,
S, N, P, O or Si heteroatom containing aryl group, carbonyl, carboxyl(ate), aldehyde,
diketo, hydroxyl, amine, imine, azo, phosphorus or sulfur containing group as a substituent
or component.
[0031] As used herein, the term "curing" is meant any process, such as addition crosslinking
or condensation, that increases the molecular weight of a polymer material or composition
through the use of the methods making or using the compositions in accordance with
the present invention. "Curable" refers to any polymer material capable of being cured
under certain conditions.
[0032] As used herein, the term "ASTM" refers to publications of ASTM International, West
Conshohocken, PA.
[0033] As used herein, the term "DSC" or "Differential Scanning Calorimetry" refers to a
method of measuring polymer cure profiles or exotherms using a Q2000TM DSC instrument
(TA Instruments, New Castle, DE). DSC was carried out using a sample of isolated uncured
polymer (<5 mg) placed in a sealed Tzero™ Aluminum hermetic sample pan (TA instruments).
The sample pan was then put in the DSC cell along with a control pan and the DSC was
then heated from RT to 300°C at a rate of 10°C per minute.
[0034] As used herein, the term "formula weight" refers to the molecular weight of a representative
formula depicting a given material.
[0035] As used herein, the term "hetero" or "heteroatom" when used referring to an organic
group means an O, P, N, S or Si atom.
[0036] As used herein, the term "NMR" refers to nuclear magnetic resonance as determined
by dissolving from 5 to 100 mg of sample material in 0.7 ml deuterated chloroform
(ACROS Organics, part of Thermo Fisher Scientific, Pittsburg, PA), then a spectrum
was obtained on a 600 MHz instrument (Bruker BioSpin Corporation, Billerica, MA) or
a 500MHz instrument (Varian, Inc, Palo Alto, CA).
[0037] As used herein, the term "oligomer" refers to relatively low molecular weight materials
such as dimers, trimers, tetramers, pentamers, hexamers, and the like that are capable
of further curing or polymerization. As used herein, an "oligoaromatic phenol compound"
or "oligoaromatic phenol resin" includes a phenol and one or more additional aromatic
rings and may have up to 30, or, preferably, up to 10 aromatic or phenyl groups, and
may be an oligophenol, such as a phenol novolac or resole.
[0038] As used herein, the term "organic alkali" means a basic reaction medium in a polar
solvent including alkyl alkali, such as an alkali alkoxide. An "organic alkali" preferably
does not include added water but may include up to 5,000 ppm of water formed by hydrolysis
or moisture in acidic or amine containing materials.
[0039] As used herein, the term "solids" refers to any materials that remain a reaction
product of the present invention; thus, solids include monomers and nonvolatile additives
that do not volatilize upon any of B-staging, polymerization and cure. Solids exclude
water, ammonia and volatile solvents.
[0040] As used herein, the term "substantially free" of a given material means that a composition
contains 1,000 ppm or less, or, preferably, 500 ppm or less of that material. As used
herein, the term "anhydrous" means substantially free of water. As used herein, unless
otherwise indicated, the term "weight average molecular weight "or "Mw" means that
value determined by gel permeation chromatography (GPC) of a polymer solution in tetrahydrofuran
(THF) at room temperature using a Waters Alliance High Pressure Liquid Chromatogram
(HPLC) (Waters, Milford, MA) equipped with an isocratic pump, an autosampler (Injection
volume (100-150 µl) and a Series of 4 Shodex™ (8 mm x 30 cm) columns, each filled
with a polystyrene divinyl benzene (PS/DVB) gel against a standard calibrated from
polystyrene as standards. As used herein, "number average molecular weight"or "Mn"
is measured in the same way as weight average molecular weight and represents the
median molecular size in a given polymer composition. As used herein, the term "PDI"
refers to the ratio of Mw/Mn
[0041] As used herein, the term "wt.%" stands for weight percent.
[0042] As used throughout this specification, the following abbreviations shall have the
following meanings, unless the context clearly indicates otherwise: °C = degree Celsius;
min. = minutes; hr. = hours; g = gram; L = liter; µm = micron = micrometer; nm = nanometer;
mm = millimeter; ml = milliliter; MPa = megapascal; Mw = weight average molecular
weight; Mn = number average molecular weight; AMU = atomic mass unit and ppm is part
per million. Unless otherwise noted, "wt.%" refers to percent by weight, based on
the total weight of a referenced composition.
[0043] In accordance with the present invention, arylcyclobutene-containing monomers or
resins, such as vinyl phenoxy BCB, allyl phenoxy BCB, amino(oligo)phenol BCB, or oligoaromatic
phenol BCB monomers or resins are synthesized in two steps from an arylcyclobutene-containing
hydrocarbon. The resulting BCB monomer has ideal curing kinetics for applications
benefitting from addition-ring opening orthogonal curing mechanisms, as determined
by differential scanning calorimetry (DSC). Further, the monomers can be thermally
copolymerized with styrene and other addition polymerizable monomers via thermal free
radical polymerization at temperatures that allow for subsequent ring opening cure.
Still further, the monomers made by the methods of the present invention are air and
benchtop stable solids at room temperature. The resulting copolymers also show thermal
stability where other phenoxy resins, such as resorcinol phenoxy BCB have been shown
to decompose.
[0044] In accordance with the methods of the present invention, deprotection of an organic
alkali cleavable protecting group, such as an alkanoyl group, from an addition polymerizable
monomer or resin, amine group containing monomer or resin or oligoaromatic compound
resin in organic alkali can be followed by reaction with an alpha-halide (a-halide)
or strong acid conjugate leaving group containing arylcyclobutene compound as a reducing
agent. The deprotection or deacylation reaction is followed by nucleophilic substitution
in the same kettle, vessel or pot. In reacting via nucleophilic substitution, the
contents of the pot are heated to a temperature of up to 80 °C. If the temperature
is too high, the materials might autopolymerize or ring open. However, despite the
relatively mild temperature of reaction, the monomer yields of methods have heterofore
not been attained.
[0045] In accordance with the methods of deprotecting or deacylating an oligoaromatic phenol
compound containing a phenolic hydroxyl of the present invention, the organic alkali
cleavable protecting group is not a phenolic group. Accordingly, the oligoaromatic
phenol compound containing a phenolic hydroxyl that results from the deprotecting
or deacylating includes one or more phenolic hydroxyl in addition to the hydroxyl
group formed by the deprotecting or deacylating.
[0046] Preferably, to prevent formation of aldehydes in the product monomer or resin of
the present invention, each of the deprotecting and the reacting via nucleophilic
substitution is carried out in anhydrous polar media.
[0047] In accordance with the present invention, the methods are suitable for making addition
polymerizable monomer materials, such as addition polymerizable arylcyclobutene-containing
monomers having one or more aryloxy, such as phenoxy, aminophenol, amino oligophenol
or oligophenolic groups. The methods in accordance with the present invention are
also useful in making arylcyclobutene compounds containing aromatic amine functional
groups or oligoaromatic phenol resins. Preferably, the methods of making monomer or
resin materials in accordance with the present invention provide addition polymerizable
arylcyclobutene compound having one or more aryloxy, such as phenoxy, oligophenolic
groups.
[0048] In addition, the methods in accordance with the present invention can provide amine
containing arylcyclobutene-containing monomers having one or more aryloxy, such as
phenoxy, or oligophenolic groups; and the methods in accordance with the present invention
can provide novolac or phenolic resin containing arylcyclobutene compounds.
[0049] The methods comprise reacting an alpha-halide (a-halide) or strong acid conjugate
arylcyclobutene-containing compound, such as a 1-bromobenzocyclobutene (a Br BCB),
with a phenol or an oligophenol containing an amine functional group, an addition
polymerizable group, such as vinyl phenol, or an oligophenol containing compound,
such as a phenolic resin. The phenol or oligophenol is itself formed by deprotecting
an addition polymerizable aromatic monomer, aromatic amine containing monomer or oligaromatic
compound containing an organic alkali cleavable protecting group, such as acetoxystyrene
or acetoxyaniline.
[0050] Preferably, the monomer composition of the present invention may comprise a monomer
B having the Structure B, below:
wherein K is a divalent group chosen from a divalent aryloxy group having from 1 to
10, or, preferably, from 1 to 6 aryl or phenol rings, or, preferably, from 1 to 6
aryl or phenol rings, or an oligophenolic group having from 1 to 10, r, preferably,
from 1 to 6 phenol units;
M is a divalent aromatic group chosen from a C1 to C6 alkyl substituted or unsubstituted aromatic radical group, or a C1 to C6 alkyl substituted or unsubstituted divalent heteroaromatic radical group;
L1 is a covalent bond; and,
R1 through R6 are each independently selected from a monovalent group chosen from hydrogen, deuterium,
halide, hydroxyl, a C1 to C6 alkyl group, a C1 to C6 alkoxy group, a C1 to C6 alkyl substituted hydrocarbon group, a heteroatom containing hydrocarbon group, a
C1 to C6 alkyl substituted heterohydrocarbon group, a cyano group, or an hydroxyl group, or
preferably, each of R1, R2 and R3 is a hydrogen, or, more preferably, each of R1 through R6 is a hydrogen.
[0051] Preferably, the methods of the present invention provide a monomer composition, such
as one comprising vinyl phenoxy BCB in which the polymerizable group is connected
the four membered BCB ring, as shown in formula I, below. The monomer is 7-((4-vinylbenzyl)oxy)bicyclo[4.2.0]octa-1(6),2,4-triene.
The present invention also enables the provision of a copolymer, such as a styrene-co-vinyl
phenoxy BCB.
[0052] In accordance with the monomer compositions of the present invention, addition polymerizable
monomer mixtures of one or more addition polymerizable arylcyclobutene-containing
monomers A having one or more aryloxy, or oligophenolic group, one or more aromatic
addition polymerizable second monomers, and, if desired, one or more other addition
polymerizable monomers chosen from an addition polymerizable nitrogen heterocycle
containing third monomer, an addition polymerizable fourth monomer, or, preferably,
both of the one or more third monomers and the one or more fourth monomers.
[0053] The monomer compositions are suitable for forming polymers by addition polymerization,
such as at temperatures of from ambient temperature to 140 °C. The resulting polymers
find use in making, for example, thin films, coatings or bulk dielectric materials,
which can be dried or soft baked at from 60 to 140 °C, followed by ring opening cure
at from 140 to 220 °C.
[0054] EXAMPLES: The present invention will now be described in detail in the following,
non-limiting Examples:
Unless otherwise stated all temperatures are room temperature (21-23 °C) and all pressures
are atmospheric pressure (-760 mm Hg or 101 kPa).
[0055] Notwithstanding other raw materials disclosed below, the following raw materials
were used in the Examples:
BCB: benzocyclobutene;
DMF: dimethylformamide;
THF: tetrahydrofuran; and,
V601: A diazo radical initiator, dimethyl 2,2'-azobis(2-methylpropionate (CAS No 2589-57-3, Wako Chemical, Japan).
[0056] Comparative Example 1: Preparation of Vinyl Phenyl Benzocyclobutene: In the following example, as shown by the equation, below a Grignard reagent undergoes
a catalyst mediated coupling to a palladium intermediate to form vinylphenyl BCB in
a poor yield.
[0057] Magnesium turnings (210mg), sodium hydride (29 mg, 60% oil dispersion) and a magnetic
stir bar were added to a 100m1 rbf, capped with a rubber septum and placed under vacuum
and allowed to stir for 4 hours. A solution of BrBCB (750 mg) in THF (20 m1) was added
via syringe slowly. The solution turned bright yellow and was placed under a nitrogen
atmosphere. The solution was left to stir for 30 minutes then added via syringe to
a 100 ml rbf containing a stir bar, bromostyrene (1 g), Pd PEPPSI-iPr(1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene)(3-chloropyridyl)palladium(II)
dichloride,
CAS no: 905459-27-0) catalyst (190 mg, 5 mol%) and THF (15 ml) under nitrogen and capped with a rubber
septum. The mixture turned black after about 30 minutes and was left to stir at room
temperature for 12h. The mixture was added to a separatory funnel containing water
(100 ml), and extracted with ethyl acetate (3x100 ml). The combined organics were
dried with brine (100 ml) and sodium sulfate, filtered and concentrated in vacuo.
The residue was recrystallized in methanol to give the desired product as a colorless
solid (203 mg, 18% yield). 1H NMR (500 MHz, Chloroform-d) σ 7.49 (d, J = 8.1 Hz, 2H),
7.44 - 7.26 (m, 6H), 6.84 (dd, J = 17.7, 10.8 Hz, 1H), 5.86 (d, J = 17.7 Hz, 1H),
5.35 (d, J = 10.8 Hz, 1 H), 4.86 - 4.75 (m, 1 H), 3.85 (dd, J = 13.9, 5.7 Hz, 1 H),
3.22 (dd, J = 13.9, 2.7 Hz, 1 H). A DSC of the resulting monomer showed an exotherm
(cure) peak max of 165 °C at a scan rate of 10 °C/min.
[0058] The yield in the above reaction was very low. Further, no ether linkage resulted
from the reaction. However, the cure temperature of the monomer was acceptable.
[0059] Example 2: Preparation of Vinyl Phenoxy Benzocyclobutene: In a 250 ml three necked round bottom flask equipped with a polytetraflouroethylene
(Teflon™ polymer, Dupont, Wilmington, DE) coated magnetic stir bar, potassium hydroxide
(1.38 g, 1 eq) was dissolved in water (6.83 g). Then, 4-acetoxy styrene (4 g, 1 eq)
was added dropwise at room temperature, and the solution turned from colorless to
pale orange. Potassium carbonate (6.82 g, 2 eq) was added portionwise, and the solution
was stirred for one hour. The flask was equipped with a reflux condenser, then 1-bromobenzocyclobutene
(4.06 g, 1 eq) was added dropwise in DMF (41 ml). The solution was then heated to
70 °C and allowed to reflux overnight. To the reaction was added water (50 ml) and
ethyl acetate (50 ml). The aqueous residue was extracted four times with ethyl acetate
(100 ml). The combined organics were extracted with sodium bicarbonate solution (1x100
ml), lithium chloride aqueous solution (1x100 ml) and brine (2x100 ml). The organics
were dried over sodium sulfate, filtered and concentrated in vacuo to give the product
as a of white solid (3.36 g, 68% yield). Melting point 54-60 °C. 1H NMR (600 MHz,
Chloroform-
d) σ 7.39 (d, J = 8.6 Hz, 2H), 7.34 (td, J = 7.3, 1.5 Hiz, 1 H), 7.31 - 7.24 (m, 2H),
7.21 - 7.18 (m, 1H), 6.98 (d, J = 8.6 Hz, 2H), 6.69 (dd, J = 17.6, 10.9 Hz, 1H), 5.70
(dd, J = 4.3, 1.9 Hz, 1H), 5.64 (dd, J = 17.6, 0.9 Hz, 1H), 5.15 (dd, J = 10.9, 0.9
Hz, 1H), 3.73 (dd, J = 14.2, 4.3 Hz, 1H), 3.31 (d, J = 14.2 Hz, 1H). 13C NMR (151
MHz, Chloroform-d)
σ 157.79, 144.62, 142.57, 136.20, 130.87, 129.93, 127.50, 127.43, 123.48, 123.04, 115.06,
111.80, 74.28, 39.45. Yield from the above example was good and the resulting monomer
was a stable solid which has a desirable ring opening cure temperature of 184 °C.
[0060] Example 3: Preparation of Vinyl Phenoxy Benzocyclobutene: To a 3L three neck reaction flask fitted with mechanical stirring (300rpm), a glass
addition funnel and a thermocouple was added acetoxystyrene and DMF. The acetoxystyrene
was sparged with nitrogen for 15 minutes, then the reactor was submerged in an ice
bath to which the thermocouple read 15 °C. A solution of sodium methoxide in methanol
(NaOMe/MeOH) was fed into the glass addition funnel, and the solution was added portion-wise
over 60 minutes, monitoring the exotherm (highest T was 21 °C). When addition was
complete, a wine red solution was observed. 1-BrBCB, DMF and a nitroxide containing
radical polymerization inhibitor (TEMPO, 2,2,6,6-Tetramethylpiperidine 1-oxyl,
CAS 2564-83-2, 25mg) were fed into the reactor and stirred for 30 minutes. The ice bath was removed
and a heating mantle was applied. The mixture was heated to 70 °C (setpoint, never
exceeded 70 °C). The mixture was stirred and tracked by NMR (d6 DMSO or d6 acetone)
and was complete after 18h. The solution darkened and a few particulates were observed.
The reactor was allowed to cool to 35 °C, then 450 ml water was added and stirred
for 10 minutes.
[0061] The mixture was transferred to a large separation funnel, and organics were dissolved
after 6000 ml of a mixture of heptanes had been added with some agitation. The bottom
aqueous layer was drained and an NMR was taken to look for remaining organic material,
which was not observed.
[0062] The organic layer was drained and stripped in vacuo wherein product was placed in
4 glass jars and cycled in vacuum 10 times over 3 days at RT to dry.
[0063] The dry product was a tan solid 586.02 g, an excellent 96% yield, 99% purity by UPLC.
The melting point and NMR spectra of the resulting monomer, 4-vinylphenoxy BCB, matched
the product isolated in Example 2, above.
[0064] Comparative Example 4: Preparation of 4-amino phenoxy BCB: In a 250 ml rbf with magnetic stir bar was added aminophenol (1 g, 1 eq), THF (15
ml) and KOtBu (1.23 g, 1.2eq). The mixture was allowed to stir for 1 hour at room
temperature. Bromo BCB (1.68 g, 1 eq) was added in THF (15 ml). The reaction was capped
and allowed to stir for 12h at room temperature. Water (100 ml) was then added. Ethyl
acetate (3x100 ml) was used to extract the product from the aqueous phase. The combined
organics were dried over sodium sulfate, filtered and concentrated in vacuo. The crude
residue was subjected to a column of silica gel using heptanes and ethyl acetate (9:1)
as eluent to give product (892 mg, 46%) as a dark oil.
1H NMR (500 MHz, Chloroform-d) σ 7.32 (dt, J = 6.6, 4.3 Hz, 1 H), 7.28 - 7.23 (m,
2H), 7.18 (d, J = 7.4 Hz, 1H), 6.86 (d, J = 9.0 Hz, 2H), 6.69 (d, J = 9.0 Hz, 2H),
5.59 (dd, J = 4.3, 2.1 Hz, 1 H), 3.66 (dd, J = 14.1, 4.3 Hz, 1 H), 3.46 (br s, 2H),
3.28 (d, J = 14.1 Hz, 1H). 13C NMR (126 MHz, Chloroform-d) σ 151.04, 145.18, 142.64,
140.49, 129.73, 127.29, 123.47, 123.00, 116.48, 116.36, 74.89, 39.47. DSC Showed an
exotherm peak temperature at 179 °C at a scan rate of 10 °C/min.
1. Propane-2,2-diylbis(2-allyl)-4,1-phenylene)diacetate; 2. 7,7'-((propane-2,2-diylbis(2-allyl)-4,1-phenylene))bis(oxy))bis(bicyclo[4.2.0]octa-1,3,5-triene);
3. 3,5-diethynylphenyl acetate; 4. 7-(3,5-diethynylphenoxy)bicyclo[4.2.0]octa-1(6),2,4-triene;
5. 3,3'-diallyl-[1,1'-biphenyl]-4,4'-diyl diacetate; 6. 7,7'-((3,3'-diallyl-[1,1'-biphenyl]-4,4'-diyl)bis(oxy))bis(bicyclo[4.2.0]octa-1(6),2,4-triene).
[0066] Example 8: Preparation of a copolymer of Vinyl Phenoxy Benzocyclobutene co Styrene: Styrene (4.77g) and vinyl phenoxy benzocyclobutene (1.13 g) were dissolved in THF
(3.98 g) along with V601™ initiator (70 mg) in an EZ Max™ 100 ml jacketed reactor
(Mettler Toledo, Columbia, MD) equipped with overhead stirring and nitrogen atmosphere.
The solution was purged with nitrogen gas for 30 minutes, then heated to an internal
temperature of 60 °C overnight. The resulting viscous solution was diluted with THF
(20 ml) then precipitated into methanol (250 ml), filtered and dried overnight in
vacuo to give the copolymer (4.23 g, 72% yield). Mn 36.6k, Mw 79.1k. The polymer curing
kinetics were evaluated via differential scanning calorimetry (DSC, TA Instruments
Q2000, TA instruments, New Castle, DE) at a ramp rate of 2, 5, 10 and 20 °C/min. The
Kissinger method was used to determine a ring opening activation barrier of 24.2 kcal/mol.
Thermal stability was evaluated using thermogravimetric analysis (TA Instruments Q5000)
under a nitrogen atmosphere, wherein a solid polymer sample was placed in a TGA pan
and run out to 400 °C at a rate of 10 °C/min.
[0067] The TGA of the resulting copolymer exhibited a five percent weight loss value at
300 °C.